1. Field of the Invention
Embodiments of the invention generally relate to an apparatus and method for polishing a substrate, such as a semiconductor wafer, more particularly, to a polishing article and apparatus for polishing a substrate utilizing an electrochemical mechanical process.
2. Description of the Related Art
In the fabrication of integrated circuits and other electronic devices on substrates, multiple layers of conductive, semiconductive, and dielectric materials are deposited on or removed from a feature side of a substrate. The sequential deposition and removal of these materials on the substrate may cause the feature side to become non-planar and require a planarization process, generally referred to as polishing, where previously deposited material is removed from the feature side of a substrate to form a generally even, planar or level surface. The process is useful in removing undesired surface topography and surface defects, such as rough surfaces, agglomerated materials, crystal lattice damage and scratches. The polishing process is also useful in forming features on a substrate by removing excess deposited material used to fill the features and to provide an even or level surface for subsequent deposition and processing.
The material removed by the planarization or polishing process may be facilitated by chemical means, mechanical means, electrical means, or a combination of chemical, electrical, and mechanical means effected, at least in part, by controllably urging the feature side of the substrate toward a polishing surface of a polishing pad. Generally, the polishing process is performed on a tool having one or more polishing stations, each station having a polishing pad or polishing article disposed thereon. Generally, each polishing station includes a polishing article on which the substrate is processed that is configured with different properties, such as hardness or compressibility, abrasiveness, smoothness, conductivity, grooving, embossment, and other physical differences selected to perform different stages of a planarization or polishing sequence at each polishing station.
One challenge facing a user of a multi-station tool is fitting each station with polishing articles having a known or otherwise predictable service life. However, due to the diverse properties of the polishing articles selected for each stage of the planarization sequence, and variations from process to process performed on each polishing station, the service life between polishing articles on a single tool is often quite different. For example, on a tool having two, three, or more, polishing stations, the polishing article lifetime may be quite different. This may increase the downtime of the tool by requiring numerous service periods to replace individual polishing articles one station at a time. While each polishing article may have a known lifetime and replacement may be scheduled, challenges to a user of a multi-station tool to increase the service life of the polishing articles disposed on each polishing station.
Therefore, what is needed is an improved polishing article for a tool having more than one polishing station that extends the service life of the polishing article relative to the remaining polishing article(s) disposed on other polishing stations.